The filter is in the computer (Lightroom), not the field - I should have been clear in my original post.
The dry lake bed in winter has no green whatsoever (think Death Valley), and the late day sun accentuated the existing yellows and golds the day I was out there. In the base files, the sky is overexposed toward white; I added the graduated filter with about -1/2 to -1 stop exposure and got the yellows you see. The graduation generally falls on the mountains.
There are also some overall color adjustments that tended toward yellow given the sunset conditions - when these shots were taken the sun was only a few degrees above the horizon, so there's a lot of atmospheric haze involved.
Given this, I do like your first interpretation, but think the second version (which you acknowledge is more toward green) is too green based on my recollection.
Thanks for the input and time spent reinterpreting the file; it is appreciated.